Densification of mounting of modules and packages has been progressed so as to realize miniaturization, weight saving and cost reduction of electronic equipments. As one of methods of high density mounting, there is exemplified a method of incorporating passive component parts such as a capacitor into a module substrate, into a mounted substrate, or on a semiconductor wafer after producing a transistor. Since electrostatic capacity of a capacitor is in proportion to a dielectric constant of an interlayer insulating film, formation of an interlayer insulating film having a large dielectric constant is advantageous to realizing a large capacity. There has hitherto been known a method in which an interlayer insulating film having a high dielectric constant is obtained by coating, drying and curing a paste composition prepared by dispersing high dielectric constant particles in a resin (see Patent Document 1). There is also known a technique in which a capacitor is produced by forming a pattern of an interlayer insulating film by a photolithography method using a composition prepared by imparting photosensitivity to polyimide having high heat resistance and dispersing high dielectric constant particles therein (see Patent Document 2).
In these prior arts, in order to stably disperse particles in a paste, an organic substance called a dispersing agent having a functional group at ends is added and the functional group of the dispersing agent is coordinated on a surface of particles thereby inhibiting approach of particles, and thus reaggregation of particles is suppressed and dispersibility of particles is improved. However, it is very difficult to completely prevent aggregation of fine particle having an average particle diameter of several tens to several hundreds of nanometer and to maintain a satisfactory dispersion state. With a conventionally known dispersing agent, insulating characteristics might deteriorate in a dielectric composition such as an interlayer insulating film obtained by curing the paste composition. Also, insulation reliability in a test of evaluating insulating characteristics by applying a voltage to a dielectric composition in a high-temperature high-humidity environment (for example, 85° C., 85% RH) (high-temperature high-humidity bias test) might be insufficient.
It was difficult for the capacitor including an interlayer insulating film made of such a material to achieve high reliability because of unstable various physical properties.    Patent Document 1: Japanese Unexamined Patent Publication (Kokai) No. 2005-38821 (patent claims)    Patent Document 2: Japanese Unexamined Patent Publication (Kokai) No. 2006-309202 (patent claims)